std.debug.assert: remove special case for test builds

Previously, std.debug.assert would `@panic` in test builds,
if the assertion failed. Now, it's always `unreachable`.

This makes release mode test builds more accurately test
the actual code that will be run.

However this requires tests to call `std.testing.expect`
rather than `std.debug.assert` to make sure output is correct.

Here is the explanation of when to use either one, copied from
the assert doc comments:

Inside a test block, it is best to use the `std.testing` module
rather than assert, because assert may not detect a test failure
in ReleaseFast and ReleaseSafe mode. Outside of a test block, assert
is the correct function to use.

closes #1304

1 files changed, 9 insertions, 8 deletions

diff --git a/std/io.zig b/std/io.zig
index 81d90def6e..d7e8507f9b 100644
--- a/std/io.zig
+++ b/std/io.zig
@@ -13,6 +13,7 @@ const trait = meta.trait;
 const Buffer = std.Buffer;
 const fmt = std.fmt;
 const File = std.os.File;
+const testing = std.testing;
 
 const is_posix = builtin.os != builtin.Os.windows;
 const is_windows = builtin.os == builtin.Os.windows;
@@ -664,7 +665,7 @@ test "io.SliceOutStream" {
     const stream = &slice_stream.stream;
 
     try stream.print("{}{}!", "Hello", "World");
-    debug.assertOrPanic(mem.eql(u8, "HelloWorld!", slice_stream.getWritten()));
+    testing.expectEqualSlices(u8, "HelloWorld!", slice_stream.getWritten());
 }
 
 var null_out_stream_state = NullOutStream.init();
@@ -726,7 +727,7 @@ test "io.CountingOutStream" {
 
     const bytes = "yay" ** 10000;
     stream.write(bytes) catch unreachable;
-    debug.assertOrPanic(counting_stream.bytes_written == bytes.len);
+    testing.expect(counting_stream.bytes_written == bytes.len);
 }
 
 pub fn BufferedOutStream(comptime Error: type) type {
@@ -1014,10 +1015,10 @@ test "io.readLineFrom" {
     );
     const stream = &mem_stream.stream;
 
-    debug.assertOrPanic(mem.eql(u8, "Line 1", try readLineFrom(stream, &buf)));
-    debug.assertOrPanic(mem.eql(u8, "Line 22", try readLineFrom(stream, &buf)));
-    debug.assertError(readLineFrom(stream, &buf), error.EndOfStream);
-    debug.assertOrPanic(mem.eql(u8, buf.toSlice(), "Line 1Line 22Line 333"));
+    testing.expectEqualSlices(u8, "Line 1", try readLineFrom(stream, &buf));
+    testing.expectEqualSlices(u8, "Line 22", try readLineFrom(stream, &buf));
+    testing.expectError(error.EndOfStream, readLineFrom(stream, &buf));
+    testing.expectEqualSlices(u8, "Line 1Line 22Line 333", buf.toSlice());
 }
 
 pub fn readLineSlice(slice: []u8) ![]u8 {
@@ -1045,8 +1046,8 @@ test "io.readLineSliceFrom" {
     );
     const stream = &mem_stream.stream;
 
-    debug.assertOrPanic(mem.eql(u8, "Line 1", try readLineSliceFrom(stream, buf[0..])));
-    debug.assertError(readLineSliceFrom(stream, buf[0..]), error.OutOfMemory);
+    testing.expectEqualSlices(u8, "Line 1", try readLineSliceFrom(stream, buf[0..]));
+    testing.expectError(error.OutOfMemory, readLineSliceFrom(stream, buf[0..]));
 }
 
 /// Creates a deserializer that deserializes types from any stream.